Pot burner for liquid fuel

ABSTRACT

A burner for combusting vaporized liquid fuel includes a combustion chamber which is open at an upper end and a side wall which defines air supply openings through which air is delivered into the combustion chamber. A thermally conductive body is disposed in the combustion chamber and extends upwards to the upper end of the chamber. The body enhances the combustion of the fuel within the combustion chamber. A disk-shaped annulus defining gas flow openings is mounted in the combustion chamber and extends radially inwards from the side wall to proximate the body, such that substantially all gas flow past the annulus occurs through the gas flow openings.

BACKGROUND OF THE INVENTION

The present invention relates to a burner for burning vapourized liquidfuel, such as diesel oil, which is intended to be introduced into apreferably, essentially cylindrical combustion chamber through a fueldelivery inlet, which is preferably located at the bottom of the burner,the combustion chamber being open at its end opposite to the bottom ofthe burner. The burner includes ignition means, such as an ignitioncoil, for initial ignition of vapourized fuel, and the combustionchamber includes holes through which air of combustion is delivered tothe combustion chamber, in which at least one essentially disk-shapedannulus or the like extends peripherally around the combustion chamberand extends radially inwards from the wall of the chamber.

Burners of this general kind are known to the art. One problem ofburners of this kind resides in effectively vapourizing the fuel, whichis normally delivered at a predetermined rate of flow per unit of timeand will thus accumulate in the combustion chamber if not vapourized.Another problem resides in achieving an effective mixture of vapourizedfuel and combustion air, so as to achieve complete combustion in theabsence of soot formations. Still another problem is one of achievingquiet combustion in the absence of pulsations.

SUMMARY OF THE INVENTION

The present invention provides a burner with which these problems aresolved in a very simple and effective manner. The burner also includescomplementary constructive features, which result in a highly effectiveand operationally reliable burner.

The invention thus relates to a burner for burning vapourized liquidfuel, such as diesel oil, which comprises a preferably cylindricalcombustion chamber to which fuel is delivered through a chamber inlet,preferably located at the bottom of the chamber, the chamber being openat the end opposite to said bottom, and further comprising an ignitionmeans, such as an ignition coil, for initial ignition of vapourizedfuel, and wherein holes are provided in the combustion chamber for thedelivery of air of combustion thereto, and wherein the combustionchamber includes at least one essentially disk-shaped annulus or thelike which extends circumferentially around the combustion chamber andprojects radially inwards from the chamber wall.

The burner is mainly characterized in that at least one body is placedpreferably centrally in the combustion chamber and extends from thebottom of the chamber to an upper part thereof and functions to assistin achieving complete combustion of the fuel delivered to the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference toexemplifying embodiments thereof and also with reference to theaccompanying drawings, in which

FIG. 1 is a vertical, schematic central sectional view of a firstembodiment of an inventive burner;

FIG. 2 illustrates schematically part of an alternative construction ofthe burner in the vicinity of a burner flame monitor;

FIG. 3 is a side view of an upper part of a cylindrical, basin-shapedbody which forms the upper part of the combustion chamber;

FIG. 4 illustrates a first embodiment of an annulus, as seen from abovein FIG. 1;

FIG. 5 illustrates another embodiment of an annulus, as seen from abovein FIG. 1; and

FIG. 6 illustrates a third embodiment of an annulus, as seen from abovein FIG. 1;

FIGS. 7A-7C illustrate the orientation of the respective levels of holesprovided in the wall of the combustion chamber; and

FIG. 8 illustrates another orientation of the holes provided in the wallof the combustion chamber.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Shown in FIG. 1 is a burner 1 for burning vapourized liquid fuel, suchas diesel oil. The burner includes an inlet 2, which in the illustratedcase is located at the bottom 3 of a preferably cylindrical combustionchamber 4, wherein fuel is introduced into the burner through the inlet2. The combustion chamber 4 is open at the end 5 thereof opposite to thebottom 3, and an ignition means 6, such as an ignition coil, is providedfor initial ignition of vapourized fuel. As described in more detailherebelow, the combustion chamber is provided with holes through whichair of combustion is delivered to the chamber.

The illustrated burner also includes a body 7 which is preferablymounted centrally in the combustion chamber 4 and which extends from thechamber bottom 3 to an upper part 8 of the combustion chamber, such asto screen-off a preferably central part of the combustion chamber. Inappropriate cases, the body is made of a material which possessesrelatively good thermal conductivity, so that an even and highcombustion temperature is obtained under high turbulence for mixingvapourized fuel with the air of combustion.

The reference numeral 9 in FIG. 1 identifies a first essentiallydisk-shaped annulus which extends circumferentially around thecombustion chamber and projects radially inwards from the wall 10thereof. The annulus 9 is mounted in the upper part 8 of the combustionchamber, the part forming the combustion zone, and extending around thebody 7 such as to define a space between the body and the annulus. Thereference numerals 11 and 12 identify annuli which are mounted beneaththe first annulus 9 and which also surround the body 7.

At least one preferably disk-shaped annulus 11 or corresponding device,FIG. 5, in this case the annulus 11, extends radially inwards from thewall 10 of the combustion chamber up to or essentially up to the body 7,so as to partition off the combustion chamber at a given level,preferably at a level substantially above the center of the verticalaxis of the chamber. The annulus 11 is provided with holes 11' throughwhich gas is intended to pass, wherein the illustrated embodimentincludes two rings of circumferentially disposed holes, i.e. an outerring and an inner ring.

The burner further includes a ring of holes 13 through which air ofcombustion is delivered to the burner and which are located in thevicinity of preferably each annulus 9, 11, 12 and at least in thevicinity of the first annulus 9. Each ring of holes is preferablyarranged above respective annuli in the immediate vicinity of the uppersurface 14 thereof. At least some, and preferably all holes 13, with theexception of the holes of the first ring of holes, of respective ringsextend horizontally, but not radially, at a given inlet angle,preferably about 40°, to the tangential direction of the wall of thecombustion chamber, as shown in FIG. 7 in the vicinity of the level ofeach annulus.

At least the ring of holes 13 which lies nearest the bottom of thecombustion chamber includes certain holes, for instance each alternatehole, which define a given inlet angle, preferably an angle of about60°, with a horizontal plane which extends transversely to the verticalaxis of the combustion chamber (FIG. 8).

According to one preferred embodiment of the invention, the annulus 12has a circle of holes 15 which extend circumferentially therearound, asillustrated in FIG. 6. The burner is preferably provided in the bottom 3with an opening 16 which is preferably located adjacent the wall 10 ofthe chamber and through which opening a flame-monitoring detector 17,such as an infrared detector, is able to detect whether the burner isignited or not. In the illustrated embodiment, a pipe 18 or like conduitextends vertically downwards from the bottom opening 16 to the vicinityof the detector 17, via a connecting pipe 19, the pipe 18 passingthrough both bottom parts 3', 3" of the illustrated burner. Thereference numeral 20 identifies an aperture which is located adjacentthe bottom opening 16 and which is formed in the pipe 18 beneath thebottom layer 3' for delivering air to a pilot flame, the status of whichis detected by the detector device.

The bottom 3 of the combustion chamber will preferably slope inwardlytowards the centre of the chamber, so that non-vapourized fuel willcollect in the centre of the burner. It is also preferred to deliverfuel to the vicinity of the bottom 3, preferably in the vicinity of theflame-monitor opening 16.

According to one preferred embodiment illustrated in the accompanyingdrawings, three disk-shaped annuli are located at mutually differentlevels in the combustion chamber. The aforesaid body 7 has a diameter ofabout 30 mm and the internal diameter of the combustion chamber is about65 mm. The central hole or throat diameter of the first annulus is about45 mm, while the throat diameter of the lowermost ring is about 40 mm.The center annulus 11 of the illustrated embodiment extends to theimmediate vicinity of the body 7. The ring of holes provided in theimmediate vicinity of the first annulus includes about 24 holes, eachhaving a diameter of 2.5 mm. The ring of holes provided in the immediatevicinity of the center annulus 11 includes about 48 holes, each having adiameter of 1.5 mm, whereas the ring of holes provided in the immediatevicinity of the annulus 12 comprises 8 holes, each having a diameter of1.6 mm. Located beneath the lowermost annulus is a ring of about 8holes, each of which has a diameter of about 1.5 mm and each alternatehole is directed downwards. The bottom ring of holes is located about 21mm from the bottom 3 of the combustion chamber, and the annuli arelocated respectively about 33.5, about 47 and about 56.5 mm from thebottom 3.

The manner in which the inventive burner operates will be understoodessentially from the aforegoing. Fuel is introduced at the bottom of theburner and is vapourized and mixed effectively with air deliveredthrough the holes. Angling of the holes results in an effective mixtureand extends the stay time. The fuel/air mixture is ignited and burnseffectively in the upper part of the combustion chamber, the upper partforming the main combustion zone. The body 7 screens-off a central partof the combustion chamber, although combustion will not normally occurin this central region of the combustion chamber to any great extent,and combustion will be concentrated to more peripheral regions of thecombustion chamber where a plentiful supply of oxygen is found. The body7 also has a heat storage effect and ensures that a uniform, hightemperature is obtained throughout the whole of the combustion chamber.The body is also able to transfer heat to the bottom region of thecombustion chamber. The body therewith ensures complete combustion ofthe fuel delivered to the burner.

The annulus 11 which extends to the immediate vicinity of the body andthrough which gas will pass solely, or essentially solely, through theholes 11' provided in the annulus 11, produces an oscillation-damping orpulsation-damping effect with regard to combustion and gas flow, sincevelocity gradients in the gas flow are quickly equalized through theholes 11' in the annulus and as a result of the pressure drop caused bythe holes. The resistance offered by the holes to the gas flow increasesrapidly with the velocity of the gas. The annulus also provides atemperature-maintaining and temperature-equalizing effect with regard,among other things, to that part of the combustion chamber which islocated beneath the annulus, and improves vapourization of the fuel andthe fuel/air mixture in addition to ensuring a high gas and flametemperature. The annulus thus contributes towards complete and effectivecombustion.

The pilot flame ensures that the burner flame can actually be detected,which is not always the case when needing to detect combustion in theupper part of the combustion chamber. As a result of thetemperature-maintaining effect of the annulus 11 and the body 7 andbecause of the downwardly directed holes in the lower ring of holes, ahigh temperature and an effective mixture is obtained in the vicinity ofthe bottom 3, so as to ensure that the pilot flame will be ignited, theignition device 6 preferably being located in the vicinity of theopening 16.

It will be evident from the aforegoing that the invention providesimportant improvements to the known technique.

Although the invention has been described with reference to preferredexemplifying embodiments thereof, it will be understood that otherembodiments are conceivable and that minor changes and modifications canbe made without departing from the concept of the invention.

It is often preferred to place the body 7 centrally and to use acylindrical body which is made of sheet metal, such as steel sheet. Thebody 7 may be solid and is conveniently screwed firmly to the bottom 3from beneath. It is also conceivable to use more than one body.Alternatively, the body, or bodies, may be made of a ceramic material.

The lower edges of the holes may be located adjacent the upper side ofrespective annuli.

Although it is preferred to include three annuli in the burner, it willbe understood that the number of annuli provided may be fewer or morethan has been shown, for instance solely the annulus 11 may be provided.

The bottom 3 is preferably clad with fiberglass fabric, which may alsoextend slightly up along the wall 10 from the bottom 3, as indicated inFIG. 1.

I claim:
 1. A burner for burning vaporized liquid fuel, comprising:acylindrical shaped combustion chamber including a side wall defining airsupply openings and an open upper end; a fuel supply inlet disposed atsaid lower end; ignition means disposed at said lower end for ignitingvaporized fuel supplied through said fuel supply inlet; an upstandingbody disposed in the combustion chamber; and a first substantiallydisk-shaped annulus extending radially inwards from said side wall ofthe combustion chamber to proximate said body so as to substantiallyclose-off the space between an inner periphery of said disk-shapedannulus and said upstanding body from the flow of gases, the firstannulus defining a plurality of gas flow openings such thatsubstantially all gases passing through the first annulus flow throughsaid gas flow openings.
 2. The burner of claim 1, wherein the combustionchamber comprises a bottom wall and said body is centrally positioned onsaid bottom wall.
 3. The burner of claim 1, wherein said side wall ofthe combustion chamber defines a plurality of circularly spaced airsupply openings disposed above and adjacent to the first annulus.
 4. Theburner of claim 1, comprising a second substantially disk-shaped annulusmounted at said upper end of the combustion chamber above the firstannulus, said second annulus extends radially inwards from said sidewall so as to define a flow space between the second annulus and saidbody.
 5. The burner of claim 3, comprising a second substantiallydisk-shaped annulus mounted at said upper end of the combustion chamberabove the first annulus, said second annulus extends radially inwardsfrom said side wall so as to define a flow space between the secondannulus and said body.
 6. The burner of claim 5, wherein said side wallof the combustion chamber defines a plurality of circularly spaced airsupply openings disposed above and adjacent to the second annulus. 7.The burner of claim 4, comprising a third substantially disc-shapedannulus mounted below the first annulus and extending radially inwardsfrom said side wall of the combustion chamber so as to define a flowspace between the third annulus and said body.
 8. The burner of claim 6,comprising a third substantially disc-shaped annulus mounted below thefirst annulus and extending radially inwardly from said side wall of thecombustion chamber so as to define a flow space between the thirdannulus and said body.
 9. The burner of claim 8, wherein said side wallof the combustion chamber defines a plurality of circularly spaced airsupply openings disposed above and adjacent to the third annulus, and aplurality of circularly spaced air supply openings disposed below thethird annulus.
 10. The burner of claim 1, wherein a number of the airsupply openings extend horizontally and form an inlet angle of about 40°with respect to a tangential direction of said side wall of thecombustion chamber.
 11. The burner of claim 9, wherein a number of theair supply openings disposed above and adjacent to the first annulus,the second annulus and the third annulus extend horizontally and form aninlet angle of about 40° with respect to a tangential direction of saidside wall of the combustion chamber.
 12. The burner of claim 11, whereina number of the air supply openings disposed below the third annulusform an inlet angle of about 40° with respect to a tangential directionof said side wall of the combustion chamber and are directed downwardsso as to form an angle of about 60° with respect to a plane extendingtransversely to a vertical axis of the combustion chamber.
 13. Theburner of claim 7, wherein the second annulus and the third annulus eachdefine a plurality of circularly spaced gas flow openings intermediatesaid outer wall of the combustion chamber and said body.
 14. The burnerof claim 1, wherein the combustion chamber comprises a bottom walldefining a bottom opening, and said burner further comprises a flamedetector for detecting the ignition of said burner through said bottomopening.
 15. The burner of claim 14, wherein said flame detector ishoused in a conduit which extends downwards from said bottom opening anddefines a flame monitoring opening, and said fuel supply inlet beingdisposed adjacent to said flame monitoring opening.
 16. The burner ofclaim 15, comprising an air passage located adjacent said bottom openingof said bottom wall for supplying air to sustain a pilot flame, saidflame detector being adapted to monitor said pilot flame.
 17. The burnerof claim 14, wherein said bottom wall of said combustion chamber issloped downwards so that vaporized fuel collects at said bottom wall.18. The burner of claim 2, wherein said body is cylindrical shaped andcomposed of a thermally conductive material.
 19. A burner for burningvaporized liquid fuel, comprising:a combustion chamber including a sidewall defining a plurality of air supply openings, a lower end and anopen upper end; a thermally conductive body disposed in the combustionchamber and extending upwardly from said lower end to said upper end; afirst horizontal wall extending inwards from said side wall of thecombustion chamber to proximate said body so as to substantiallyclose-off the space between an inner periphery of said first horizontalwall and said thermally conductive body from the flow of gases, thefirst wall defining a plurality of gas flow openings such thatsubstantially all gases passing through the first wall flow through thegas flow openings; a second horizontal wall mounted at said upper end ofthe combustion chamber above the first annulus, the second wallextending radially inwards from said side wall so as to define a flowspace between the second wall and said body; and a third horizontal wallmounted below the first annulus and extending radially inwards from saidside wall of the combustion chamber so as to define a flow space betweenthe third wall and said body.
 20. A burner for burning vaporized liquidfuel, comprising:a combustion chamber including a side wall, a lower endand an open upper end, said side wall defining a plurality of circularlyspaced air supply openings extending horizontally and forming an inletangle of about 40° with respect to a tangential direction of said sidewall; a fuel supply inlet disposed at said lower end; ignition meansdisposed at said lower end for igniting vaporized liquid fuel suppliedthrough said fuel supply inlet; a thermally conductive body disposed inthe combustion chamber and extending upwardly from said lower end tosaid upper end; a first substantially disk-shaped wall extendinginwardly from said side wall of the combustion chamber to proximate saidbody to substantially close-off the space between an inner periphery ofsaid first disc-shaped wall and said thermally conductive body from theflow of gases, the first wall defining a plurality of gas flow openingssuch that substantially all gases passing through the first wall flowthrough the gas flow openings; a second substantially disk-shaped wallmounted at said upper end of the combustion chamber above the firstwall, the second wall extending radially inwards from said side wall soas to define a floor space between the second wall and said body; athird substantially disk-shaped wall mounted below the first wall andextending radially inwards from said side wall of the combustion chamberso as to define a flow space between the third wall and said body; saidside wall of the combustion chamber defining a plurality of circularspaced air supply openings disposed below the third wall and forming aninlet angle of about 40° with respect to the tangential direction ofsaid side wall and being directed downwards so as to form an angle ofabout 60° with respect to a plane extending transversely to a verticalaxis of the combustion chamber; and a flame detector disposed at saidlower end of the combustion chamber for detecting ignition of saidburner.